Observations on guinea pig inclusion conjunctivitis agent

Chlamydia pneumoniae encodes a functional aromatic amino acid hydroxylase

Chlamydia pneumoniae is a community-acquired respiratory pathogen that has been associated with the development of atherosclerosis. Analysis of the C. pneumoniae genome identified a gene (Cpn1046) homologous to eukaryotic aromatic amino acid hydroxylases (AroAA-Hs). AroAA-Hs hydroxylate phenylalanine, tyrosine, and tryptophan into tyrosine, dihydroxyphenylalanine, and 5-hydroxytryptophan, respectively. Sequence analysis of Cpn1046 demonstrated that residues essential for AroAA-H enzymatic function are conserved and that a subset of Chlamydia species contain an AroAA-H homolog. The chlamydial AroAA-Hs are transcriptionally linked to a putative bacterial membrane transport protein. We determined that recombinant Cpn1046 is able to hydroxylate phenylalanine, tyrosine, and tryptophan with roughly equivalent activity for all three substrates. Cpn1046 is expressed within 24 h of infection, allowing C. pneumoniae to hydroxylate host stores of aromatic amino acids during the period of logarithmic bacterial growth. From these results we can conclude that C. pneumoniae, as well as a subset of other Chlamydia species, encode an AroAA-H that is able to use all three aromatic amino acids as substrates. The maintenance of this gene within a number of Chlamydia suggests that the enzyme may have an important role in shaping the metabolism or overall pathogenesis of these bacteria.

Chlamydiales in guinea-pigs and their zoonotic potential

The aim was to detect and characterize chlamydial infections in guinea-pigs (GP) with ocular disease, study their pathogenicity and zoonotic potential and to test for the presence of Acanthamoebae spp. in GP eyes and to investigate whether they could act as vectors for Chlamydia-like organisms. Overall 126 GP, of which 77 were symptomatic, were screened by clinical examination, cytology, gross pathology, histology, immunohistochemistry, polymerase chain reaction (PCR) and bacteriology. A new Chlamydiaceae-specific intergenic spacer rRNA gene PCR, designed to amplify this segment linking the 16S and 23S regions, was performed. DNA samples were also received from one owner including samples of his cat and rabbit. Guinea-pigs: 48 of 75 symptomatic, but only 11 of 48 asymptomatic GP were positive by PCR for Chlamydophila caviae guinea-pig inclusion conjunctivitis (GPIC) (P < 0.0001). Eighteen of 75 or 15/48, respectively, were positive for DNA from Chlamydia-like organisms. Acanthamoebae-DNA could be found in two GP, of which one was symptomatic. Owner, cat and rabbit: Samples of all three species were positive by PCR for C. caviae GPIC and the owner's one-day disposable contact lenses showed a positive PCR result for the Chlamydia-like organism Parachlamydia acanthamoebae. No Acanthamoebae-DNA could be detected. This study is the first to describe Chlamydia-like organisms in GP and to detect C. caviae GPIC in human, cat and rabbit. Therefore, C. caviae GPIC could pose a zoonotic potential. We believe that the finding of C. caviae GPIC in species other than GP is probably not unique.

Chlamydia and Chlamydiales: more than meets the eye

This review summarizes the dramatic changes that have occurred in the taxonomy of bacteria known as Chlamydia. Best known for the diseases they cause in humans, these intracellular bacteria also comprise many species that are responsible for a wide variety of clinically and economically important diseases in livestock and companion animals. The old taxonomy grouped most of these species into C. psittaci because systematic methods for routinely distinguishing them were not available. DNA-based testing methods are now available that distinguish different chlamydial families, genera, and species. This summary reviews these tests and a number of oligonucleotide primers that distinguish these groups using PCR and PCR-RFLP. DNA-based methods are also being used to discover new families of chlamydia-like bacteria, at least one of which is responsible for abortion in cattle (Waddlia chondrophila). This review summarizes the pathogenic roles of the Chlamydiaceae, new families, and individual species within the order Chlamydiales. These discoveries create opportunities for veterinarians to carry out epidemiological studies of chlamydiae that previously were not possible.

Guinea-pig inclusion conjunctivitis as a model for the study of trachoma: clinical, microbiological, serological, and cytological studies of primary infection

The course of primary ocular infection with guinea-pig inclusion conjunctivitis agent was followed in 2 groups of animals. One group of fully grown animals was repeatedly scraped; the other of small animals was used on 1 occasion only and scraped after clinical examination. The intensity of conjunctival inflammation was measured, conjunctival scrapings were taken, and the numbers of polymorphonuclear cells, mononuclear cells, and epithelial cells containing chlamydial inclusions were counted, and the level of antibodies in serum was measured. It was found that inflammation of the conjunctiva lasted for about 30 to 40 days, and the clinical features (oedema, hyperaemia, papillary reaction) were very similar in the 2 groups. Inclusions and polymorphonuclear cells were found for up to 21 days, and mononuclear cells were found on days 7 to 25. Serum antibodies were first detected on day 10 and reached a peak on day 21. The intensity of inflammation was significantly higher on day 2 in the animals which had been scraped. After this the severity of the inflammation and the course of disease were similar in the 2 groups.

Immunity to vaginal reinfection in female guinea pigs infected sexually with Chlamydia of guinea pig inclusion conjunctivitis

Guinea pig boars were inoculated intraurethrally with the chlamydial agent of guinea pig inclusion conjunctivitis (GPIC). At the heights of their urethral infections, they were caged with sows in estrus. Whereas some of the sows had not been previously exposed to GPIC agent, others had received an intravaginal inoculation 5 to 8 weeks earlier. Those sows for which infected boars provided the first exposure were challenged by intravaginal inoculation 5 to 8 weeks later. Vaginal and conjunctival scrapings were taken regularly and stained for chlamydial inclusions. Titers of serum anti-GPIC antibodies and of vaginal secretory IgA anti-GPIC antibodies were determined by immunofluorescence. Our results show for the first time that a sexually acquired vaginal GPIC infection induces immunity to manual reinfection of the vagina. Because of the high incidence of secondary conjunctival infections among the vaginally infected sows, we could not provide a sound statistical basis for our tentative conclusion that manual infection of the vagina induces immunity to sexual reinfection. The results of our antibody titrations confirm previous work showing that vaginal GPIC infection induces formation of both serum antibody and vaginal secretory immunoglobulin A antibody.

Infection of genital tract and transmission of ocular infection to newborns by the agent of guinea pig inclusion conjunctivitis

Female guinea pigs were inoculated intravaginally with the agent of guinea pig inclusion conjunctivitis (Gp-ic). Evidence for infection was obtained by demonstration of Gp-ic inclusions in epithelial cells of genital tract smears, histopathology, recovery of Gp-ic during infection, and antibody response. Infection of the genital tract was produced with low doses (20-200 median egg lethal doses) of the agent. The infection lasted about 3 weeks, and there was no marked clinical response. Ocular infection that could be detected as early as 3 days after birth in offspring of infected mothers was also demonstrated.